it allows the primary to breath to the trans......yes, needed.

 

Aren’t you a scientist? How many thousands of an inch clearance is needed to allow gas to pass? It’s not like your primary is breathing like the motor, it’s just heating up and the air or gases if you prefer are expanding. It’s not like there’s a huge amount of volume or pressure.

 

Why not put a vent on trans and primary and eliminate any pressure differential.

 

A coal geophysicist yes lol. I don’t claim to be any expert on anything automotive, just passing on what I’d been told by the maker.

 

A vent on the primary should help, I'll do that. The transmission already has one.
Guess I'll have to try a rod without a flat...

 

You mean the MoCo?

 

Oh cool, I'll make it a little different then.

 

So you tried one with the flat and it did not work?

 

The flat just never seemed necessary to me. If anything, machining or grinding just one side of the rod could cause it to warp some. Not saying that it ever did, just a possibility.

 

While I can understand that the flat is not needed, I was just questioning the preference for the "non flattened" rod. Was it a case where the flatten rod did not work or simply an observed preference.

If the rod were made with something like 1018 cold rolled steel, the cut could cause the rod to curve as there is a lot of stress in material from the process. I would assume that the 4130 (?) was stress relieved possibly to some hardness so it probably is not an issue.